The present invention relates to a method for transmitting announcements from a traffic information warning service which makes use of Digital Audio Broadcasting (DAB), and to a receiver for receiving and for selectively reproducing (playing back).
At the present time, traffic announcements for road users are made up of announcements broadcast by analog transmitters. The digital traffic information warning service, Radio Data System (RDS), comprising a Traffic Message Channel (TMC), constitutes a further development. The structure and the coding of the digital traffic information messages are defined in CEN Draft pr. ENV/278/4/1/0011, which is based on the proposed standard Alert C, November 1990, published by RDS ATT Alert Consortium. In this context, the essential elements of a traffic information message are the location of the event (location) and the event. These pieces of information are cataloged, i.e., a unique code is assigned to each location and event that are relevant to traffic. The locations are concatenated in the table of locations along existing streets to reproduce the sequence. Besides the usual receiver devices comprising a decoder, to make use of the Traffic Message Channel TMC, devices are needed for decoding, storing, further processing, and for outputting the traffic information message. Speech conversion is required to decode these digitally coded traffic information messages. This is associated with substantial complexity, so that in countries or regions of small populations where a certain language is spoken, one should not expect that any TMC system will be introduced in the foreseeable future. However, in contrast to traffic information messages of the TMC system, traffic information messages as announcementsxe2x80x94described as traffic announcements in the followingxe2x80x94are not able to be selected with respect to their geographic allocation.
At the same time, one has to expect that digital broadcasting of the Digital Audio Broadcasting (DAB) will become more and more prevalent. Compared to the old analog methods, digital broadcasting has the advantage of a much more reliable reception, with a sound quality comparable to that of a CD. The specifications of digital sound broadcasting are defined in ETS 300401, February 1995. To transmit the TMC messages, provision is made in the digital sound broadcasting protocol for a channel, i.e., the Fast Information Channel (FIC). However, the terminal equipment currently available for digital sound broadcasting still does not include any decoder for TMC messages. Thus, at the present time, in digital sound broadcasting, it is only the traffic information messages integrated in the sound broadcast program which can be output, which, however, as in the case of the analog method, can neither be selected nor managed in any way.
In contrast, the advantage of the method of the present invention is that the digital transmission of the sound broadcast renders possible a simple allocation to the data of the digital traffic information warning system. Another advantage is that the transmission of TMC data via digital radio broadcasting is carried out much more effectively, since reception difficulties are much less when working with the digital method. This is especially useful in regions having multipath reception (mountains, multi-story buildings, or cities) and/or in regions serviced by transmitters that broadcast ARI at the same time.
It is especially beneficial to link the TMC messages in the FIC data channel and the traffic announcements in the digital radio with the help of data blocks, so-called link objects. In this case, the uniqueness of the allocation is assured because of the parallelism of the transmission and the connection to the transmitter.
It is advantageous for the beginning and the end of a traffic announcement in the digital radio to be signaled by a speaker pressing a button, the signaling being handled by the TMC transmission control.
In another advantageous embodiment, the data of the traffic announcement are not transmitted by the actual sound broadcast program, instead separately transmitted audio segments are used. This makes it possible for spoken announcements to be transmitted in different languages and, thus, for the correct language to be selected in the receiver. One advantageous exemplary embodiment of a receiver, which makes it possible for spoken announcements to be received in accordance with the method of the present invention, contains a DAB decoder, as well as a TMC decoder and a corresponding management device.